1. Field of the Invention
The present invention relates to a catalyst and its use in a catalytic cracking process. More particularly, the present invention relates to a cracking catalyst that minimizes coke production.
2. Description of Information Disclosures
Hydrocarbon cracking catalysts comprising a zeolite and discrete particles of phosphorus-treated alumina dispersed in an inorganic oxide matrix are known. See, for example, U.S. Pat. No. 4,567,152.
U.S. Pat. No. 4,456,780 discloses a hydrocarbon disproportionation process using a zeolite having a silica to alumina ratio of at least 12 Which has been pretreated with a phosphorus-containing compound and Which may additionally have been steamed prior to said treatment.
U.S. Pat. No. 4,454,241 discloses a phosphorus-containing zeolitic catalyst made from a clay starting material. The catalyst is obtained by contacting a partially cation exchanged calcium zeolite-containing catalyst with a dihydrogen phosphate anion, e.g., ammonium hydrogen phosphate or dihydrogen phosphite anion.
U.S. Pat. No. 4,430,199 discloses passivation of contaminant metals on cracking catalyst by phosphorus addition. The phosphorus compound may be ammonium hydrogen phosphate. The phosphorus compound may be impregnated on an inert carrier such as calcined metakaolin clay that can be blended with the catalyst or added to the catalyst. See column 3, lines 17 to 20, and column 10, lines 20 to 25.
It has now been found that a catalytic cracking process utilizing catalysts comprising zeolites that have been pretreated with certain phosphorus compounds will produce less coke and gas relative to utilizing the same catalyst that does not comprise a phosphorus-treated zeolite.